Hi dawn here third hilo. 56 female and retired
I have a 1990 30 ft br and the interior wood frame for seal, blocks has dry rot along the inside seal edge. very common, and the screws rusted, and block feel off. I Purchased an angle bracket for wood joining a 2x4 corner (about 4inch by 4 inch,) took metal grinder with cutting wheel and cut one leg of the 90 degree bracket to the height and width of the slider. Then let the bottom edge point out to even with the outside frame which is steel. removed lower trim. slipped bracket up. drilled holes in outside edge which is steel frame, four screws. mounted the block to bracket by drilling four holes nut bolt and ground the excess screw off . This added under quarter of inch between original frame area and bracket. as the wood was soft bracket actually settled in. Has stayed square runs up and down nicely. did this with two others.
and yes in theory should raise top replace all wood etc. etc. this took about two hours.
cost 5 dollars including screws lol. As side note anti freeze sprayed onto dryrot will stop the process, boat builders use it all the time. I back filled with spray in insulating foam that expands and hardens. not perfect. But keeps water out of area